Use the modern "portable" _clearfp() and _controlfp(), that work
regardless of the hardware MS is running on, rather than the
x86-specific _clear87() and _control87(); and move some defines into
the #if-ery context in which they're used, rather than defining them
regardless of whether they're used.
Change-Id: I13abf2c85525b1182b99bc2c366aadd6b5fc656f
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
67a563e5c5